Stabiliser, jetting and circulating tool

ABSTRACT

A downhole tool ( 10 ) for use in oil and/or gas well bores. The tool has a tubular body ( 20 ) and a sleeve ( 22 ) including stabiliser blades ( 30 ). The tool is ball ( 76 ), activated, weight activated or hydraulically activated to selectively jet fluid from the body through jetting ports ( 44 A,  44 B,  44 C) on the blades. Thus the tool provides the features of a stabiliser, cleaning tool and circulation tool in-one.

The present invention relates to downhole tools used in oil and gaswells and in particular to a downhole tool which provides the combinedfunctions of stabilising, jetting fluid and circulating fluid within thewell bore.

In drilling or completing a well bore, it has been recognised thatsignificant time and cost savings can be made if a number of toolsproviding different functions can be mounted on the same work string andrun together into the well bore. Each tool mounted on the work stringmust be capable of being operated independently. A large number ofmethods of operating tools on a work string have been developed and theytypically include ball activated, weight activated or hydraulicallyactivated tools.

However there are disadvantages in providing so many tools on a workstring. The location of each tool within the well bore must beconsidered so that the string requires minimal repositioning andreciprocation in the well bore to operate each tool. Additionally thetime and requirements in making up the string prior to the run must becarefully considered as the string can have an excessive working length.

It would therefore be advantageous to provide a downhole tool for use ona work string which can provide a plurality of functions within the wellbore and therefore reduce the number of tools which require to bemounted on a work string.

It is an object of the present invention to provide a downhole toolwhich can operate in a number of functional modes simultaneously withina well bore.

It is a further object of at least one embodiment of the presentinvention to provide a downhole tool which performs the functions ofstabilising, jetting and circulating fluid simultaneously within a wellbore.

It is a further object of at least one embodiment of the presentinvention to provide a downhole tool in which one or more functions canbe selectively performed from a selection of functions on the tool.

According to a first aspect of the present invention there is provided adownhole tool for use in a well bore, the tool comprising;

-   -   a tubular body having an axial throughbore and adapted for        connection within a work string;    -   a sleeve mounted around the body, the sleeve including one or        more stabiliser blades, said stabiliser blades including one        more jetting ports to direct fluid from the axial throughbore        onto a surface of the well bore; and    -   one or more actuating means to selectively direct the fluid        through the jetting ports and thereby circulate the fluid.

Thus, the downhole tool of the present invention provides a stabilisingfunction, a jetting function for cleaning and a fluid circulatingfunction within a well bore. It will be appreciated that the term wellbore covers tubulars such as a casing or liner located in the bore.

Preferably, the one or more actuating means provides a cyclic function.That is the one or more actuating means can be operated to provide atleast one cycle wherein each cycle is an on/off/on or alternatively anoff/on/off function with respect to the exit of fluid through thejetting ports.

In a preferred embodiment of the present invention, the actuating meansprovides two cycles.

Preferably also, the actuating means is selected from a group comprisingball activated, weight activated and hydraulically activated or acombination thereof.

Preferably, the sleeve is threaded onto the body. More preferably, thethread is a left-hand thread and thus advantageously the sleeve willtighten while rotating. Preferably, also, the outer diameter of thestabiliser blades on the sleeve are sized to be close to the innerdiameter of the tubular in use. Thus, a large outer diameter of the toolprovided at the stabiliser blades will improve the jettingeffectiveness. Preferably, the stabiliser blades are arranged in ahelical pattern around the sleeve. More preferably, there is atriangular flow-by groove between adjacent stabiliser blades. Suchtriangular flow-by grooves minimise cutting action on the surface of thewell bore.

Preferably, the/each stabiliser blade has a central portion including asurface parallel to the axial throughbore. Advantageously, the one ormore jetting ports are arranged on the parallel surface of thestabiliser blades. Thus, the jetting ports are arranged at the closestposition to the surface of the well bore.

Preferably also the blades include a milling surface. Preferably, themilling surface is at a leading end of the work string. Advantageously,the milling surface is of tungsten carbide to provide a reaming orcutting function and assist the tool in clearing obstacles and/orremoving debris from the surface of the well bore.

The jetting ports may be arranged substantially perpendicular to theaxial throughbore. More preferably, one or more jetting ports arearranged at an angle to the perpendicular to provide a larger cleaningsurface against the surface of the well bore when the fluid is jetted.

Advantageously, each jetting port includes a nozzle. The nozzle may belocated at an exit of the jetting port. The nozzles reduce the diameteravailable for fluid flow and thereby increase the velocity of the flowas it exits the tool. Advantageously, each nozzle is located below theouter surface of the sleeve. This provides an advantage in allowing wearof the tool to occur without obstructing the nozzle so that the nozzlesmay be removed and installed easily.

Preferably, a channel is located between the body and the sleeve.Preferably, also, the jetting ports access the channel. Advantageously,the one or more actuating means direct fluid from the axial throughboreto the channel prior to the fluid flowing through the jetting ports.Thus, as the same jetting ports are used, each time the actuating meansoperates, this minimises the potential for leaks within the tool.

Embodiments of the present invention will now be described, by way ofexample only, with reference to the following Figures in which:

FIG. 1 is a part cross-sectional schematic view of a downhole toolaccording to a preferred embodiment of the present invention;

FIG. 2 is a cross-sectional schematic view of the actuating means usedin the tool of FIG. 1. Figures (a), (b) and (c) illustrate the actuatingpositions of the tool.

FIG. 3 shows an alternative actuating means, which may be used in thedownhole tool of the present invention.

Reference is initially made to FIG. 1 of the drawings, which illustratesa downhole tool generally indicated by Reference Numeral 10, accordingto a preferred embodiment of the present invention. Tool 10 has an upperend, including a box section 14 for connection in a work string (notshown). Tool 10 also has a lower end 16, which includes a pin section 18for connection in a work string mounted below the tool 10. It will beappreciated that although the references to upper and lower are providedit will be understood by those skilled in the art that the downhole toolof the present invention could be used in a vertical, inclined or ahorizontal position in a well bore. It will further be appreciated thatthe tool of the present invention has application within a well boreduring drilling operation or in a cased or lined well bore where atubular has been inserted during completion.

Tool 10 comprises a tubular body 20. A sleeve 22, is mounted around thebody 20, and is held in place by a threaded connection 24. The thread isleft-handed so that when the tool is rotated the sleeve 22 will betightened onto the body 20. O-rings 26, 28 are located between the body20 and the sleeve 22, to prevent the ingress of dirt or the outflow ofpressure between body 20 and the sleeve 22.

Mounted on sleeve 22 are a number of blades 30. Blades 30 are arrangedin a helical or spiral pattern on the sleeve 22. Each blade has alongitudinal body 32 with a sloping front face 34 and a sloping backface 36. The front face 34 has a hardened surface 38, which partlyextends onto a planar surface 40 between the sloping faces 34, 36. Thehardened surface 38 allows the blades 30 to contact debris or otherobstacles within the well bore and mill them or clean them off.

Between the blades 30 are located channels 42. The channels 42 have atriangular cross-section and act as flow-by grooves between the bladesto minimise cutting action of the blades on the formation in the wellbore. Located on the planar section 40 of each blade are three jettingports 44A, B and C. Each port 44 A, B and C provides access between aback surface 46 of the sleeve 22 and a front surface 48 of the sleeve22.

The inlet ports 44A, B and C are arranged so that the central port 44Bis perpendicular to a central bore 50 which runs through the body 20while the ports 44A and C are angled with respect to port 44B. Each port44 includes a nozzle 52, which reduces the diameter of the port 44 andthereby increases the speed of fluid passing through the port 44. Eachport 44, contacts a channel 54, located between the body 20 and thesleeve 22. This channel houses fluid and the o-rings 26, 28 prevent thefluid from escaping from the tool 10 by means other than those providedat ports 44.

Within the body 20 there are located two inlet ports, 56, 58. Each inletport 56, 58 is associated with an actuating means 60, 62. The actuatingmeans 60, 62 are primarily located within the central bore 50. Theactuating means 60, 62 control the passage of fluid within the centralbore 50, through the ports 56, 58 respectively and into channel 54. Thiscontrols the passage of fluid out of the tool via the inlet ports 44. Itwill be appreciated that although only one inlet port 56, 58 isassociated with each actuating means 60, 62 there may be any number ofinlet ports 56, 58 and equally any number of actuating means 60, 62 aslong as the fluid from each is located within the channel 54.

Reference is now made to FIG. 2 of the drawings which illustrate anactuating means, generally indicated by Reference Numeral 62, as wouldbe found in the tool of FIG. 1. Like parts to those of FIG. 1 have beengiven the same Reference Numerals to aid interpretation. The actuatingmeans 62 is a drop ball activation means as would typically be found ina downhole tool. An example of such a downhole tool would be U.S. Pat.No. 6,253,861 to Specialised Petroleum Services Group Limited, thepresent Applicant. U.S. Pat. No. 6,253,861 is hereby incorporated byreference.

Actuating means 62 comprises first 64 and second 66 sleeves arrangedconcentrically within the body 20. Each sleeve, 64, 66 includes arespective port 68, 70. The ports 68, 70 provide access through thesleeves 64,66. It will be appreciated that each port 68, 70 generallycomprises a plurality of ports circumferentially arranged on the sleeve64, 66. As shown in Figure (a) the sleeves are initially arranged sideby side and held together via a shear pin 72. Further, the pair ofsleeves 64,66 are held to the body by means of a second shear pin 74.Shear pin 74 is located through the body 20 and into the first sleeve64.

In use, the tool 10 is run into the well bore or tubular. The diameterof the tool 10 at the blades 30 would be selected to provide a smallclearance between the tool and the surface of the well bore or tubular.A typical clearance may be a number of millimetres.

Once located at the point where fluid is required to be jetted orcirculated a drop ball 76 is inserted into the central bore 50 to travelthrough the body and locate in a ball seat 78 of the second sleeve 66.Ball 76 blocks the axial passage of fluid through the bore 50 and as aresult pressure will build up on an upper surface 80 of the ball 76. Theincrease in pressure will shear the pin 74 and allow the sleeves 66, 64to move axially through the bore 50. The sleeves 64, 66 will movetogether by virtue of the shear pin 72. The sleeves 64, 66 travel to astop 82. At the stop 82 the sleeve 64 and 66 are positioned such thatthe ports 68 and 70 align with the port 58 and thereby allow fluid inthe bore 50 to enter a channel 54 and exit the jetting ports 44.

Once the jetting and circulation requirement is complete the tool 10 canbe closed as shown in FIG. 2(c) by virtue of a second drop ball 84 beinginserted through the bore 50. Ball 84 is a larger diameter than ball 76and locates on a ball seat 86 on the second sleeve 66. Ball 84 preventsthe passage of fluid through the bore 50 and thereby pressure increaseson its upper surface 88 until the shear pin 72 shears and the sleeves 64and 66 disengage from each other. On disengagement the innermost sleeve66 will fall relative to the outer sleeve 64. The innermost sleeve fallsa distance to a second stop. In this position a by-pass channel 90 inthe first sleeve 64 provides a passage of fluid around the drop ball 84.Similarly, at drop ball 76 a by-pass passage towards the body 20 is nowaccessed from ports 92 in the sleeve 66.

Thus, in the closed position the port 70 of the inner sleeve 66 is nowmisaligned with the port 66 of the outer sleeve and the port 58 leadingto the channel 54. By the insertion of two drop balls, the tool hasperformed one cyclic function in taking the jets 44 from a closedposition to an open position and again to a closed position.

Referring back to FIG. 1, it will be seen that a similar actuating meansas shown in FIG. 2 can be located at position 60 and through port 56. Asecond cyclic motion can be performed. In this regard, a twin cycle ispossible with tool 10 and thus by timed insertions of drop balls ofsufficient diameter the jetting ports 44 can function in a selective onor off position.

As will be appreciated by those skilled in the art the actuator means60,62 in FIG. 1 may be replaced by any actuator means which causesselective opening and closing of a channel 56, 58 into the channel 54 togive access to the ports 44.

Reference is now made to FIG. 3 of the drawings which illustrates aportion of a circulation tool generally indicated by Reference Numeral100 which could be used as the actuating means 60, 62 of a downhole toolof the present invention. Like parts to those of FIG. 1 have been giventhe same Reference Numeral. As with FIG. 1, the actuator means 100 ispositioned on the body 20 which has a central bore 50. The actuatormeans comprises a sleeve 102 located on the body 20 which is biasedagainst the body by means of a helical spring 104 housed between ledges105, 107 on the sleeve 102 and body 20 respectively. Located in thesleeve 102 are two vent holes 106, 108, which permit the equalisation ofpressure outside the sleeve 102 with pressures between the sleeve 102and the body 20. Located in the sleeve 102 are a plurality of ports 130.Also mounted on the body 20 are five O-ring seals 112, which sealinglyengage with the sleeve 102. On the inside of the sleeve 102 adjacent tocirculating ports 110 is an internal groove 114 found on the innersurface of the sleeve 102.

Below the sleeve 102 is a spring tensioner ring 116 which is threadablyengaged to the body 20 through a thread formation 117. A set screw 124is provided to lock the spring tensioner 116 in position on the body 20.

The spring tensioner 116 has a single shoulder 118 to which hard facingin the form of tungsten carbide 119 is applied. At the lower end of thesleeve 102 adjacent to spring tensioner ring 116, an actuating shoulder120 is provided.

The actuating element 100 is moved by virtue of the shoulder 120contacting a formation in the well bore. This formation may be the upperedge of a liner or polished bore receptacle. Initially when the shoulder120 contacts the formation, the tool remains in the position shown inthe Figure. In this position the ports 110 are obturated by the sleeve112 and fluid can be pumped through the bore 50. Weight can then be setdown upon the tool 10, this weight causes the body 20 to drop relativeto the sleeve 102 and the helical spring 104 will be compressed. Travelof the sleeve 102 is limited by a shoulder 125 contacting a surface 127formed as a lock on the body 20. This helps prevent the spring 104becoming spring bound. When the shoulder 125 abuts against the lock 127the groove 114 is adjacent to the ports 110 and the ports 110 in thebody 20 communicate with a ports 130 on the sleeve 102. It will beappreciated that ports 130 are equivalent to the ports 56, 58 of FIG. 1and thus fluid from the bore 50 again can pass into channel 54. To closethe ports 130 weight is lifted off the tool and the spring 104 biasesthe sleeve 102 to return to the position shown in FIG. 3.

A principal advantage of the present invention is that it combines anumber of functions on a single tool within a well bore. A furtheradvantage of the present invention is that it can provide an increasedannulus velocity for hole cleaning due to the small clearance providedbetween the ports 44 and the inner surface of the well bore or tubularin use.

It will be appreciated by those skilled in the art that this tool canreplace a conventional stabiliser used in a bottom hole assembly.Further, drilling can be performed with this tool mounted in the bottomhole assembly and the tool can be also used to pump mud while drilling.Alternatively, the tool can be used to jet clean the low pressurehousing, the high pressure well head and downhole casing adapterprofile, as it is more effective than using the bit and does not requirean extra trip into the well. The tool can further be run in conjunctionwith a mud motor and can be used to shut down the bit at the shoe tominimise casing wear while pumping. It will also be appreciated that thetool may be run in conjunction with an under reamer and can be used todeactivate blades at a shoe. Thus it can be used in preference todropping a dart.

Advantageously the present invention provides a large outer diameterjetting and circulating device that acts as a drilling stabiliser aswell and can be activated by different means one or more times. Thus,specific areas within the well can be jetted at various times withoutretrieval of the string from the well.

Various modifications may be made to the invention herein describedwithout departing from the scope thereof. Primarily it will beappreciated that any actuating means which provides selective openingand closing of a channel in the body of the tool may be incorporated asone or more of the actuating means in the tool of the present invention.

1. A downhole tool for use in a well bore, the tool comprising: atubular body having an axial throughbore and adapted for connectionwithin a work string; a sleeve mounted around the body, the sleeveincluding one or more stabiliser blades, said stabiliser bladesincluding one more jetting ports to direct fluid from the axialthroughbore onto a surface of the well bore; and one or more actuatingmeans to selectively direct the fluid through the jetting ports andthereby circulate the fluid.
 2. A downhole tool as claimed in claim 1wherein the one or more actuating means provides a cyclic on/offfunction.
 3. A downhole tool as claimed in claim 1 wherein the actuatingmeans is selected from a group comprising ball activated, weightactivated and hydraulically activated or a combination thereof.
 4. Adownhole tool as claimed claim 1 wherein the sleeve is threaded onto thebody by a left-hand screw thread.
 5. A downhole tool as claimed claim 1wherein an outer diameter of the stabiliser blades on the sleeve aresized to be close to the inner diameter of the tubular in use.
 6. Adownhole tool as claimed claim 1 wherein the stabiliser blades arearranged in a helical pattern around the sleeve.
 7. A downhole tool asclaimed in claim 1 wherein the tool includes a triangular flow-bygroove, between adjacent stabiliser blades.
 8. A downhole tool asclaimed in claim 1 wherein each stabiliser blade has a central portionincluding a surface parallel to the axial throughbore, on which arearranged the one or more jetting ports.
 9. A downhole tool as claimed inclaim 1 wherein the blades include a milling surface.
 10. A downholetool as claimed in claim 1 wherein one or more of the jetting portsinclude a nozzle, located below an outer surface of the blade.
 11. Adownhole tool as claimed in claim 1 wherein a channel is located betweenthe body and the sleeve, accessed by the jetting ports.
 12. A downholetool as claimed in claim 11 wherein the one or more actuating meansselectively direct fluid from the axial throughbore to the channel.